In the daily ever-competing society, those who can control information are winner of tomorrow; therefore the computer has become a prerequisite, useful and effective tool in the information age: it is more and more widespread that the people use computer to process numerous and complicated data, and nowadays the internet is prevailing, computer plays a very important role which is inseparable form the information procurement and liaison as well as multiplex information, transmission between each other. In the circumstances for along time, the so-called computer syndrome appears, and the working personnel in front of the computer terminals are under the effect and threat of radiation intangibly and unknowingly in general and the pregnant women among them in particular. Now there are the so-called computer goggles and protective nets, but their effect is poor, and in fact, hey can partially screen the electromagnetic waves from the display tube but cannot fully eliminate the threat from radiation effect.
Next, all the electrical appliances including computer will generate the AC electromagnetic waves of 60 Hz very low frequency which is normally called as electromagnetic radiation or low-frequency radiation as soon they as turned on. As a close-distance and long-time operational electrical appliance, the computer generates a low-frequency radiation ranging form 60 Hz to 200 megahertz and having an effect on the human body which is quite concerned about by the medical, scientific and technological professionals. So how to effectively eliminate the electromagnetic radiation of computer becomes a large subject matter to be settled by the computer manufacturers.
With regard to the elimination of computer electromagnetic radiation at the present of time, there are the following two methods:
1. In the aspect of manufacturing factory, it is separated with an electromagnetic screening device which is built in the computer to prevent the electromagnetic radiation generated during the circuit operation; however the expected effect cannot be achieved without a fine grounding measure. PA1 2. In the aspect of user, it is eliminated with a correct housing ground, namely, the electromagnetic radiation is absorbed by the electromagnetic screening device and then eliminated through the housing ground. Even the computer manufacturers designed it very well but the users cannot put it into practice in reality (for example, they use the conventional 2-hole type power source socket),and the original design cannot develop its effect.
Therefore, regardless of the present computer with a built-in electromagnetic screening device or not, and in spite of the grounding device of computer itself able to develop its effect or not, the electromagnetic radiation leakage and existence of computer are directly affected.
Those who frequently contact the computer know that the power source wire plug of computer has three legs wherein two flat legs are NULL and LIFE of power source, and the third leg is round as the ground point of computer housing to let the user develop the effect of electromagnetic screening, to prevent leakage and to lessen the electronic-magnetic radiation not necessarily accepted by the human body to a minimum extent. In Europe, America and a number of advanced countries, the power source has been required to adopt 3-hole type socket wherein one hole is used to connect the ground wire buried in the building itself, it is foolproof that the electrical appliance grounding is quite important. It is regrettable that now many countries including Taiwan region remain using 2-hole type power source socket, so the computer users in general, when installing a computer after purchasing it, have to, first of all, remove the round leg, namely the third leg, from its power source wire plug, then they can smoothly insert it into the 2-hole type socket; however, when the said third leg is removed therefrom, the screening effect of computer electromagnetic radiation is ineffective, and the users continuously suffer the prohibitive electromagnetic radiation since they don't know it.